1. Field of the Invention
The invention relates to a control of a vehicle, more particularly, to a control of a hybrid vehicle.
2. Description of Related Art
In recent years, taking environmental issues into account, hybrid vehicles that efficiently combine an engine and an electric motor have been put into practical use. Such hybrid vehicles are equipped with a rechargeable battery, and propel itself using an electric motor by supplying the electric motor with electric power from the battery at the time of launch or acceleration. In contrast, at the time of braking or the like, kinetic energy of the vehicle is converted by the electric motor into electric power, which is recovered into the battery
Japanese Patent Application Publication No. 2010-47218 (JP-A-2010-47218) describes a plug-in hybrid vehicle, the traveling of the vehicle is performed by selecting one of a mode in which an EV travel in which the engine is stopped and the vehicle travels by motive power from the electric motor is given priority, and a mode in which an HV travel in which the vehicle travels by motive power from both the engine and the electric motor is permitted.
In addition, Japanese Patent Application Publication No. 2008-168806 (JP-A-2008-168806) describes a hybrid vehicle equipped with different engine start conditions.
Exhaust gas from an engine contains pollutants such as hydrocarbon, carbon monoxide, nitrogen oxides, etc. These pollutants are substantially removed by a catalyst that is provided in the exhaust pipe of the engine. However, depending on the state of the engine, the amount of the pollutants in the exhaust sometimes exceeds the purification capacity of the catalyst. Therefore, it is desirable to accurately detect deterioration of the quantity of engine exhaust.